FIELD OF THE INVENTION
The present invention relates to a cooling and moistening unit for rotary printing machines, in particular for rotary printing machines for processing material webs.
The published German Patent Document DE 44 35 275 A1 concerns a device and a method for processing a material web. A device for dissipating heat from a web includes a chill roll with a cylindrical outer surface. The web is moved along a path which extends partly around the chill roll. Between the two side parts of the web, a nozzle extends in the circumferential direction around part of the cylindrical outer surface of the chill roll. Through the central part of the nozzle, an air flow is directed towards a central part of the web, specifically above a location at which the web normally comes into contact with the chill roll, in order to cause the central part of the web to sag and in this way to bring that part into contact with the chill roll. Lateral nozzle parts extend to both sides of the central part of the nozzle, specifically underneath the location at which the central part of the web is caused to sag in the direction of the chill roll. As a result, smoothing is achieved in the transverse direction and along the central part of the web.
The published German Patent Document DE 197 10 124 A1 concerns a method and a device for controlling the temperature of chill rolls. The publication relates to the cooling of a printed or coated material web, which, in particular, has been printed by the offset printing process and is formed of paper. After the application of ink, the material web has passed through a heating zone and is led over a multiplicity of chill rolls of a chill-roll stand. In this regard, the flow of the cooling medium through the chill rolls of a chill-roll stand is produced by two different cooling circuits at different temperature levels and is directed over the chill rolls counter to the web running direction of a material web. In this embodiment, the chill rolls are arranged in a conventional manner, taking up a considerable amount of construction and erection space, and only two of the chill rolls are arranged above one another.
The published European Patent Document EP 0 627 311 B1 is concerned with a web cooling device. The device according to this publication permits the cooling of a printing-material web heated in a dryer of a web-fed printing machine, using a supporting roll or turning device disposed downline of the dryer and guiding the printing-material web. By means of a second roll disposed downline of the supporting roll or turning device and guiding the printing-material web, with a first liquid applicator roll for applying liquid to a first side of the printing-material web, and a second liquid applicator roll for applying liquid to a second side of the printing-material web. The liquid applicator rolls are arranged on mutually opposite sides of the printing-material web, between the supporting roll or the turning device and the second roll. According to the disclosed device, the liquid applicator rolls are together assigned to a section of the printing-material web travelling between the supporting roll or turning device and the second roll, and are arranged to be offset relative to one another. They produce a pressure contact with the printing-material web along a contact surface in such a manner that dampening of the printing-material web surfaces can be effected.
However, by this proposed construction according to the published European Patent Document EP 0 627 311 B1, only a limited number of chill rolls can be accommodated in one chill-roll stand, as a result of which the effectiveness of the device for cooling remains limited, whereby a low temperature, at which a cooled material web is supposed to leave the device according to this published patent document, is difficult to achieve.
In the course of the general technical development in the printing sector, web speeds have continuously increased. Consequently, longer dryers and longer chill-roll units have now become necessary in order to achieve the drying of the printed material web and the cooling of the heated material web within an acceptable time interval following drying. From the indicated development, there results the problem, on the one hand, of reaching higher printing-machine speeds and, on the other hand, of keeping the lengths of dryers or cooling and redampening units, respectively, within a tolerable length with regard to the costly adjusting or erection area in print shops or printing plants.